|
1
|
Lin YS, Tsay RY. Drug Release from a Spherical Matrix: Theoretical Analysis for a Finite Dissolution Rate Affected by Geometric Shape of Dispersed Drugs. Pharmaceutics 2020; 12:pharmaceutics12060582. [PMID: 32585967 PMCID: PMC7357057 DOI: 10.3390/pharmaceutics12060582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/02/2022] Open
Abstract
Amending the neglect of finite dissolution in traditional release models, this study proposed a more generalized drug release model considering the simultaneous dissolution and diffusion procedure from a drug-loaded spherical matrix. How the shape factor (n = 0, 1/2, and 2/3 for the planar, cylindrical, and spherical geometry, respectively) of dispersed drug particles affected the release from the matrix was examined for the first time. Numerical solutions of this generalized model were validated by consensus with a short-time analytical solution for planar drugs and by the approach of the diffusion-controlled limits with Higuchi’s model. The drug release rate increases with the ratio of dissolution/diffusion rate (G) and the ratio of solubility/drug loading (K) but decreases with the shape factor of drug particles. A zero-order release profile is identified for planar drugs before starting the surface depletion layer, and also found for cylindrical and spherical dispersed drugs when K and G are small, i.e. the loaded drug is mainly un-dissolved and the drug release rate is dissolution-controlled. It is also shown that for the case of a small G value, the variation of drug release profile, due to the drug particle geometry, becomes prominent. Detailed comparison with the results of the traditional Higuchi’s model indicates that Higuchi’s model can be applied only when G is large because of the assumption of an instantaneous dissolution. For K = 1/101–1/2, the present analysis suggests an error of 33–85% for drug release predicted by Higuchi’s model for G = 100, 14–44% error for G = 101, while a less than 5% error for G ≧ 103.
Collapse
Affiliation(s)
- Yung-Sheng Lin
- Department of Chemical Engineering, National United University, Miaoli 36063, Taiwan
- Correspondence: (Y.-S.L.); (R.-Y.T.); Tel.: +886-37-38-2199 (Y.-S.L.); +886-2-2826-7024 (R.-Y.T.)
| | - Ruey-Yug Tsay
- Department of Biomedical Engineering, National Yang-Ming University, Taipei 11221, Taiwan
- Center for Advanced Pharmaceutics and Drug Delivery Research, National Yang-Ming University, Taipei 11221, Taiwan
- Correspondence: (Y.-S.L.); (R.-Y.T.); Tel.: +886-37-38-2199 (Y.-S.L.); +886-2-2826-7024 (R.-Y.T.)
| |
Collapse
|
|
2
|
Liu S, Yu J, Li H, Wang K, Wu G, Wang B, Liu M, Zhang Y, Wang P, Zhang J, Wu J, Jing Y, Li F, Zhang M. Controllable Drug Release Behavior of Polylactic Acid (PLA) Surgical Suture Coating with Ciprofloxacin (CPFX)-Polycaprolactone (PCL)/Polyglycolide (PGA). Polymers (Basel) 2020; 12:E288. [PMID: 32024179 PMCID: PMC7077375 DOI: 10.3390/polym12020288] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/28/2020] [Accepted: 01/30/2020] [Indexed: 02/07/2023] Open
Abstract
Polylactic acid (PLA) surgical suture can be absorbed by human body. In order to avoid surgical site infections (SSIs), the drug is usually loaded on the PLA suture, and then the drug can release directly to the wound. Because the different types of wounds heal at different times, it is needed to control the drug release rate of PLA suture to consistent to the wound healing time. Two biopolymers, polyglycolide (PGA) and polycaprolactone (PCL), were selected as the carrier of ciprofloxacin (CPFX) drug, and then the CPFX-PCL/PGA was coated on the PLA suture. The degradation rate of drug-carrier can be controlled by adjusting the proportion of PCL/PGA, which can regulate the rate of CPFX drug release from PLA suture. The results show that the surface of PLA suture, coating with PCL/PGA, was very rough, which led to increased stitching resistance when we were suturing the wound. These materials, such as the PLA suture, the PCL/PGA carriers and the CPFX drug, were just physically mixed rather than chemically reacted, which was very useful for ensuring the original efficacy of CPFX drug. With the increasing of PCL in the carriers, both the breaking strength and elongation of these un-degraded sutures increased. During degradation, the breaking strength of all sutures gradually decreased, and the more PCL in the coating materials, the longer effective strength-time for the suture. With the increasing of PCL in the drug-carrier, the rate of drug releasing became lower. The drug release mechanism of CPFX-PCL/PGA was a synergistic effect of drug diffusion and PCL/PGA carrier dissolution.
Collapse
Affiliation(s)
- Shuqiang Liu
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
- Biomedical Textile Laboratory, Taiyuan University of Technology, Jinzhong 030600, China
| | - Juanjuan Yu
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Huimin Li
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Kaiwen Wang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Gaihong Wu
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Bowen Wang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Mingfang Liu
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Yao Zhang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Peng Wang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Jie Zhang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Jie Wu
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Yifan Jing
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
| | - Fu Li
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
- Biomedical Textile Laboratory, Taiyuan University of Technology, Jinzhong 030600, China
| | - Man Zhang
- College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China; (J.Y.); (H.L.); (K.W.); (B.W.); (M.L.); (Y.Z.); (P.W.); (J.Z.); (J.W.); (Y.J.); (F.L.); (M.Z.)
- Biomedical Textile Laboratory, Taiyuan University of Technology, Jinzhong 030600, China
| |
Collapse
|
|
3
|
Gajula K, Gupta R, Sridhar DB, Rai B. In-Silico Skin Model: A Multiscale Simulation Study of Drug Transport. J Chem Inf Model 2017; 57:2027-2034. [PMID: 28718641 DOI: 10.1021/acs.jcim.7b00224] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Accurate in-silico models are required to predict the release of drug molecules through skin in order to supplement the in-vivo experiments for faster development/testing of drugs. The upper most layer of the skin, stratum corneum (SC), offers the main resistance for permeation of actives. Most of the SC's molecular level models comprise cholesterol and phospholipids only, which is far from reality. In this study we have implemented a multiscale modeling framework to obtain the release profile of three drugs, namely, caffeine, fentanyl, and naphthol, through skin SC. We report for the first time diffusion of drugs through a realistic skin molecular model comprised of ceramides, cholesterol, and free fatty acid. The diffusion coefficients of drugs in the SC lipid matrix were determined from multiple constrained molecular dynamics simulations. The calculated diffusion coefficients were then used in the macroscopic models to predict the release profiles of drugs through the SC. The obtained release profiles were in good agreement with available experimental data. The partition coefficient exhibits a greater effect on the release profiles. The reported multiscale modeling framework would provide insight into the delivery mechanisms of the drugs through the skin and shall act as a guiding tool in performing targeted experiments to come up with a suitable delivery system.
Collapse
Affiliation(s)
- Kishore Gajula
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - Rakesh Gupta
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - D B Sridhar
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| | - Beena Rai
- Physical Sciences Research Area, TCS Research, Tata Research Development and Design Centre, Tata Consultancy Services , 54B, Hadapsar Industrial Estate, Pune-411013, India
| |
Collapse
|
|
4
|
Snorradóttir BS, Jónsdóttir F, Sigurdsson ST, Másson M. Numerical modelling of transdermal delivery from matrix systems: parametric study and experimental validation with silicone matrices. J Pharm Sci 2014; 103:2366-75. [PMID: 24984880 DOI: 10.1002/jps.24052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/12/2014] [Accepted: 05/16/2014] [Indexed: 11/12/2022]
Abstract
A model is presented for transdermal drug delivery from single-layered silicone matrix systems. The work is based on our previous results that, in particular, extend the well-known Higuchi model. Recently, we have introduced a numerical transient model describing matrix systems where the drug dissolution can be non-instantaneous. Furthermore, our model can describe complex interactions within a multi-layered matrix and the matrix to skin boundary. The power of the modelling approach presented here is further illustrated by allowing the possibility of a donor solution. The model is validated by a comparison with experimental data, as well as validating the parameter values against each other, using various configurations with donor solution, silicone matrix and skin. Our results show that the model is a good approximation to real multi-layered delivery systems. The model offers the ability of comparing drug release for ibuprofen and diclofenac, which cannot be analysed by the Higuchi model because the dissolution in the latter case turns out to be limited. The experiments and numerical model outlined in this study could also be adjusted to more general formulations, which enhances the utility of the numerical model as a design tool for the development of drug-loaded matrices for trans-membrane and transdermal delivery.
Collapse
|
|
5
|
Application of numerical methods for diffusion-based modeling of skin permeation. Adv Drug Deliv Rev 2013; 65:208-20. [PMID: 22261307 DOI: 10.1016/j.addr.2012.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 12/23/2011] [Accepted: 01/03/2012] [Indexed: 11/22/2022]
Abstract
The application of numerical methods for mechanistic, diffusion-based modeling of skin permeation is reviewed. Methods considered here are finite difference, method of lines, finite element, finite volume, random walk, cellular automata, and smoothed particle hydrodynamics. First the methods are briefly explained with rudimentary mathematical underpinnings. Current state of the art numerical models are described, and then a chronological overview of published models is provided. Key findings and insights of reviewed models are highlighted. Model results support a primarily transcellular pathway with anisotropic lipid transport. Future endeavors would benefit from a fundamental analysis of drug/vehicle/skin interactions.
Collapse
|
|
6
|
Naegel A, Heisig M, Wittum G. Detailed modeling of skin penetration--an overview. Adv Drug Deliv Rev 2013; 65:191-207. [PMID: 23142646 DOI: 10.1016/j.addr.2012.10.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 06/28/2012] [Accepted: 10/17/2012] [Indexed: 11/20/2022]
Abstract
In recent years, the combination of computational modeling and experiments has become a useful tool that is proving increasingly powerful for explaining biological complexity. As computational power is increasing, scientists are able to explore ever more complex models in finer detail and to explain very complex real world data. This work provides an overview of one-, two- and three-dimensional diffusion models for penetration into mammalian skin. Besides diffusive transport this includes also binding of substances to skin proteins and metabolism. These models are based on partial differential equations that describe the spatial evolution of the transport process through the biological barrier skin. Furthermore, the work focuses on analytical and numerical techniques for this type of equations such as discretization schemes or homogenization (upscaling) techniques. Finally, the work compares different geometry models with respect to the permeability.
Collapse
Affiliation(s)
- Arne Naegel
- Frankfurt University, Goethe Center for Scientific Computing, Kettenhofweg 139, 60325 Frankfurt am Main, Germany
| | | | | |
Collapse
|
|
7
|
Dukhin SS, Labib ME. Theory of effective drug release from medical implants based on the Higuchi model and physico-chemical hydrodynamics. Colloids Surf A Physicochem Eng Asp 2012; 409:10-20. [PMID: 24155569 DOI: 10.1016/j.colsurfa.2012.04.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Combining the approach of colloid transport with the generalized Higuchi theory of drug release and with the concept of minimum inhibitory concentration (MIC) known in microbiology, the theory of effective drug release from implants has been developed. Effective release of an antibiotic at a concentration above MIC is a necessary condition to achieve protection against infection from implants such as central catheters. The Higuchi theory in its present form is not predictive of the therapeutic effect from medical implants. The theory of effective release presented in this paper specifies two release modes, namely: one with therapeutic usefulness (effective release) and another without therapeutic effect. Therapeutic usefulness may be achieved when the antibiotic concentration, Cti , on the implant surface kills the organisms of interest and prevents the formation and propagation of biofilm when Cti exceeds the corresponding MIC of the released antibiotic compound. Currently, neither the Higuchi theory nor any other theory can provide such prediction. The present approach requires quantification of the antibiotic transport from the drug-polymer blend implant surface into the tissue and accounts for its coupling with drug diffusion inside the blend, a task that has not been developed in existing theories. Our solution to this task resulted in the derivation of an equation for the time of duration of effective release, Te , which depends on MIC, the Higuchi invariant and the characteristics of convective diffusion within the tissue. The latter characteristics include: diffusivity Dti and diffusion layer thickness δ which is controlled by the velocity of the interstitial fluid in tissue. A smaller Dti is favorable because transport from the catheter surface is weaker, while a thinner diffusion layer is harmful because this transport is stronger. The influence of the tangential component of interstitial velocity in the tissue is especially harmful because the diffusion within the incision exit site (IES) will be extremely enhanced such that it may decrease Cti to zero. The incorporation of convective diffusion into the theory of antibacterial protection by means of antibiotic release has revealed that physicochemical mechanisms predict the effectiveness of antibiotic-loaded catheters and defines the conditions necessary to achieve better protection by means of combining the level of catheter loading with antibiotics and the use of wound (IES) dressing.
Collapse
|
|
8
|
Lee PI. Modeling of drug release from matrix systems involving moving boundaries: Approximate analytical solutions. Int J Pharm 2011; 418:18-27. [DOI: 10.1016/j.ijpharm.2011.01.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 12/28/2010] [Accepted: 01/07/2011] [Indexed: 11/16/2022]
|
|
9
|
Frenning G. Modelling drug release from inert matrix systems: From moving-boundary to continuous-field descriptions. Int J Pharm 2011; 418:88-99. [DOI: 10.1016/j.ijpharm.2010.11.030] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 11/10/2010] [Accepted: 11/12/2010] [Indexed: 10/18/2022]
|
|
10
|
Labib ME, Brumlik CJ, Stoodley P, Dukhin SS, Davidson T, Tabani Y. The Long-term Release of Antibiotics From Monolithic Nonporous Polymer Implants for Use as Tympanostomy Tubes. Colloids Surf A Physicochem Eng Asp 2010; 254:331-337. [PMID: 21614132 DOI: 10.1016/j.colsurfa.2009.10.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A technology is elaborated for the fabrication of a novel tympanostomy tube (TT) from solidified polymer melts (Elvax and Polyurethane) and antibiotics (Ciprofloxacin and Usnic acid) for insertion into tympanic membrane (ear drum) according to the established surgical procedure. The long-term in vitro release kinetics of the antibiotics into liquid water has been assessed using standard methods. The measured kinetic curves revealed two stages of antibiotic release into the finite space. During the first stage (fast), the fast release rate is almost invariant and is determined by the diffusion through the steady diffusion layer formed due to solution agitation. In this first stage, the influence of the initial internal transport is weak because it takes place at negligibly small distance from interface and accordingly, at negligibly concentration drop. After the antibiotic concentration decreases within the much broader layer of matrix near interface, the internal transport becomes important. This manifests itself as the second stage in measured kinetics of release curves which is characterized by a gradual decrease in rate. The minimum inhibition concentrations of three antibiotics/antimicrobial compounds for four bacterial species were measured. The first stage of fast release from the polymer implant lasts 6 days at a polymer loading by Ciprofloxacin (0.03 g/cm(3)) and this was sufficient for preventing biofilm formation on the surface of the implant material. The measured kinetic curves of drug release showed more rapid decrease in the release rate compared to the Higuchi approximation. Comparison with existing theories, which account for the finite rate of drug dissolution, showed that this may explain the observed deviation from the diffusion-controlled Higuchi model. Large dimensions of drug particles and their aggregation retard the dissolution stage and consequently the release rate. Melt blending was found to cause the drug particle aggregation within polymer matrixes which was confirmed by microscopic reexamination of the polymer implant materials.
Collapse
Affiliation(s)
- Mohamed E Labib
- Novaflux Technologies, 1 Wall Street, Princeton, NJ 08540, U.S.A
| | | | | | | | | | | |
Collapse
|
|
11
|
Barocas V, Drasler W, Girton T, Guler I, Knapp D, Moeller J, Parsonage E. A dissolution-diffusion model for the TAXUS™ drug-eluting stent with surface burst estimated from continuum percolation. J Biomed Mater Res B Appl Biomater 2008; 90:267-74. [DOI: 10.1002/jbm.b.31282] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
|
12
|
Frenning G, Brohede U, Strømme M. Finite element analysis of the release of slowly dissolving drugs from cylindrical matrix systems. J Control Release 2005; 107:320-9. [PMID: 16081182 DOI: 10.1016/j.jconrel.2005.06.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 05/17/2005] [Accepted: 06/30/2005] [Indexed: 11/25/2022]
Abstract
Drug release from matrix systems of cylindrical shape is analyzed in detail by using the finite element method. The model used combines the Noyes-Whitney and diffusion equations, and thus takes the effects of a finite dissolution rate into account. The model is valid for all drug solubilities and dissolution rates, and allows accurate predictions of the drug release to be made. Anisotropic drug transport that may result from the manufacturing process is properly accounted for. Model calculations show that a finite dissolution rate may affect the release profile significantly, producing an initial delay. The equivalence between anisotropic release and isotropic release from a matrix with different dimensions is demonstrated. Comparisons are made with the predictions of a recently proposed pseudo-steady state (PSS) analysis of drug release from cylindrical matrices [Y. Zhou, J. S. Chu, T. Zhou, X. Y. Wu, Modeling of dispersed-drug release from two-dimensional matrix tablets, Biomaterials 26 (2005) 945-952]. This comparison reveals that important discrepancies exist between the numerical and analytical results, which are attributed to the simplifying assumption made in the PSS analysis that the region containing solid drug remains cylindrical in shape throughout the release process. The proposed model is shown to describe experimental release data well.
Collapse
Affiliation(s)
- Göran Frenning
- Department of Pharmacy, Uppsala University, Uppsala Biomedical Center, P. O. Box 580, SE-751 23 Uppsala, Sweden.
| | | | | |
Collapse
|
|
13
|
Frenning G. Theoretical investigation of drug release from planar matrix systems: effects of a finite dissolution rate. J Control Release 2003; 92:331-9. [PMID: 14568413 DOI: 10.1016/s0168-3659(03)00338-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Drug release from planar matrix systems has been investigated with special emphasis on the influence of a finite dissolution rate on the drug release profile. A mathematical model of the drug dissolution and release processes was formulated in terms of two coupled nonlinear partial differential equations (PDEs). These were solved numerically by using well-established FORTRAN routines. An approximate analytical solution, valid during the early stages of the release process, was derived. The analytical solution was compared to the numerical one and to drug release models existing in the literature. From this comparison, it was established that the analytical approximation provided a good description of the major part of the release profile, irrespective of the dissolution rate. Existing literature models, based on instantaneous dissolution, were found to agree with the numerical solution only when drug dissolution proceeded very rapidly in comparison with the diffusion process. Consequently, the new analytical short-time approximation of the drug release complements the formulas existing in the literature, since it provides a superior description of the release of slowly dissolving drugs.
Collapse
Affiliation(s)
- Göran Frenning
- Department of Pharmacy, Uppsala University, P.O. Box 580, SE-751 23, Uppsala, Sweden.
| |
Collapse
|
|
14
|
Tipre DN, Vavia PR. Formulation optimization and stability study of transdermal therapeutic system of nicorandil. Pharm Dev Technol 2003; 7:325-32. [PMID: 12229264 DOI: 10.1081/pdt-120005729] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this research investigation was to fabricate acrylate-based stable transdermal therapeutic system (TTS) of nicorandil, which could deliver drug through transdermal route. Monolithic TTS was fabricated in pressure sensitive adhesives (PSAs)--(a) terpolymer (PSA1) of 2-ethylhexyl acrylate, methyl methacrylate, and acrylic acid, (b) copolymer (PSA2) of 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and vinyl acetate, and (c) Eudragit E100 pressure sensitive adhesive (PSA3). To enhance the flux of nicorandil, skin permeation enhancer N-methyl-2-pyrrolidone (NMP) was investigated at different concentrations (0.05-5%) in PSAs. Fabricated TTS was evaluated for in-vitro release and skin permeation through guinea pig skin. Maximum flux of nicorandil was observed from Eudragit E100 based TTS and kept for stability study at refrigeration, 25 degrees C/30% RH and 30 degrees C/60% RH. Patches were evaluated for various physicochemical parameters. Formulation was observed to be relatively more stable at refrigeration. Shelf life of the formulation was found to be 270, 270, and 30 days at refrigeration, 25 degrees C/30% RH and 30 degrees C/60% RH conditions, respectively. Nicorandil could be successfully derived from Eudragit E100 based TTS, but attention needs to be given to improve its chemical stability in formulation.
Collapse
Affiliation(s)
- Dnyanesh N Tipre
- University Department of Chemical Technology, Pharmaceutical Division, University of Mumbai, Matunga, Mumbai 400 019, India
| | | |
Collapse
|
|
15
|
Abstract
The objective of the present research investigation was to fabricate an acrylate-based transdermal therapeutic system (TTS) of nitrendipine, which could deliver drug at maximum input rate so as to deliver drug in minimum patch size. Transdermal patches were fabricated using synthesized acrylate pressure-sensitive adhesives (PSAs): PSA1, PSA2, and commercially available PSA3 and PSA4 using d-limonene as permeation enhancer. Effect of concentration of d-limonene on permeation kinetics of nitrendipine in PSAs was studied. Fabricated TTS in mentioned PSAs were evaluated for in-vitro release and permeation kinetics through guinea-pig skin. Cumulative release of drug in PSA1, PSA2, PSA3, and PSA4 was observed to be 45%, 40%, 25%, and 25%, respectively, upto 24 hr. Flux of drug through guinea-pig skin calculated at 48 hr in PSA1, PSA2, PSA3, and PSA4, with and without d-limonene, was observed to be 0.346+/-0.10, 0.435+/-0.17, 0.410+/-0.17, and 0.162+/-0.06, and 0.625+/-0.19, 1.161+/-0.46, 0.506+/-0.17, and 0.520+/-0.18 (microg/cm2/hr), respectively. The TTS in PSA2 showed comparatively high flux and could deliver drug at high input rate through transdermal route. PSA2 was found to have good rate-controlling property and could be successfully employed in transdermal delivery of nitrendipine.
Collapse
Affiliation(s)
- Dnyanesh N Tipre
- University Department of Chemical Technology, Pharmaceutical Division, University of Mumbai, Matunga, Mumbai, India
| | | |
Collapse
|
|
16
|
Wu XY, Zhou Y. Studies of diffusional release of a dispersed solute from polymeric matrixes by finite element method. J Pharm Sci 1999; 88:1050-7. [PMID: 10514355 DOI: 10.1021/js9804361] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper presents systematic analyses by the finite element method of release kinetics of a dispersed solute from various matrixes (i.e. , slab, sphere, cylinder, and convex tablet), with or without boundary-layer resistance, into a finite or an infinite external volume. In the case of sink conditions, the numerical results agree well with the existing analytical solutions. For the problems of solute release into a finite external volume, where the analytical solutions are not available, this work has provided numerical solutions of the differential equations describing the release kinetics, moving boundaries, and concentration profiles. This work has also revealed the dependence of release kinetics on the initial solute loading, the external volume, and the boundary-layer thickness. The method presented here can describe the entire process of diffusional release before and after the dispersed solute has been dissolved without the pseudo steady-state assumption and it is applicable to both small and large ratio of initial solute loading to the solute solubility in the matrix.
Collapse
Affiliation(s)
- X Y Wu
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S 2S2.
| | | |
Collapse
|
|
17
|
Kubota K, Twizell EH, Maibach HI. Drug release from a suspension with a finite dissolution rate: theory and its application to a betamethasone 17-valerate patch. J Pharm Sci 1994; 83:1593-9. [PMID: 7891281 DOI: 10.1002/jps.2600831115] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A random walk method for a diffusion equation is applied to the model for a suspension with a finite dissolution rate developed by Ayres and Lindstrom in 1977. In the method, the diffusion of dissolved drug and dissolution of crystal are calculated separately using a simple BASIC program. The random walk method strictly meets the principle of the conservation of mass as the drug amount in each sublayer rather than the concentration at each subinterval is concerned in the ointment. The model is used to analyze the release of betamethasone 17-valerate from a pressure-sensitive silicone adhesive into a sink. The drug release from the 1.50 mg/mL patch shows no substantial discrepancy from that predicted by the classic suspension model assuming an infinite dissolution rate. However, the classic model overestimates the release from the 3.08 and 5.88 mg/mL patches. The disagreement is lessened when the dissolution rate is assumed to be finite. However, the model does not give a perfect explanation because the drug release from the 3.08 and 5.88 mg/mL patches in the early phase is faster than the model predicts.
Collapse
Affiliation(s)
- K Kubota
- Department of Dermatology, University of California--San Francisco, School of Medicine 94143-0989
| | | | | |
Collapse
|
|
18
|
Kubota K, Yamada T, Ogura A, Ishizaki T. A novel differentiation method of vehicle models for topically applied drugs: application to a therapeutic timolol patch. J Pharm Sci 1990; 79:179-84. [PMID: 2324968 DOI: 10.1002/jps.2600790220] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A novel method to differentiate basic vehicle models for topically applied drugs is proposed. In this method, the rate of drug release as a function of time, obtained by using a flow-through cell, is plotted on both semilogarithmic and logarithmic scales. In the Solution Case, where all of the drug is dissolved in the vehicle, the profiles become linear on the semilogarithmic scale. However, in the Suspension Case, where the initial drug amount per vehicle volume is greater than the solubility of the drug and the vehicle contains finely dispersed drug, the profiles are linear on the logarithmic scale with a slope of -0.5. They abruptly depart from this pattern upon depletion of the suspended phase. The different attributes of the profiles for the drug release rate-time curves in these two cases can be visualized more clearly when vehicle thickness and drug concentration are varied. The theoretical principles are illustrated in profiles for the drug release-rate time plots of therapeutic patches containing the beta blocker timolol. This was formulated at different concentrations in an acryl copolymer with varied thickness. The release profiles were best fitted to the Solution Case treatment of the data.
Collapse
Affiliation(s)
- K Kubota
- Division of Clinical Pharmacology, National Medical Center, Tokyo, Japan
| | | | | | | |
Collapse
|
|
19
|
Ayres JW, Lindstrom FT. Diffusion model for drug release from suspensions I: theoretical considerations. J Pharm Sci 1977; 66:654-62. [PMID: 874746 DOI: 10.1002/jps.2600660513] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A new mathematical model based on physicochemical principles is presented; it does not require a "diffusion layer" for the release of a suspended drug from a semisolid vehicle. This general model has wide range application to systems where release is controlled by the diffusion rate or dissolution rate of a drug. The appropriate mathematical relationships are derived and evaluated. Theoretical drug concentration distributions in the vehicle and a membrane and the predicted cumulative drug mass uptake by blood under specified conditions are presented. The dissolution rate of solid drug in the vehicle markedly influences predicted drug release using the model presented. It is anticipated that the model will stimulate further research to confirm or reject the assumption that the dissolution rate may be slow enough to be important in the systems studied.
Collapse
|